Method for Recognizing Available Channel in Ieee 802.15.4 Protocol Csma/Ca Mechanism

1. A method of recognizing an available channel in order to prevent channel occupation requirements from colliding with each other when one wireless channel is shared by plural terminals in a CSMA/CA mechanism using an IEEE 802.15.4 protocol slot, in which a backoff time varies by allocating different backoff exponents (BEs) for determining a random backoff time, the method comprising: initializing, by a processor, a CW counter, as 2; determining, by the processor, if a channel is occupied; decreasing, by the processor, the CW counter by 1 when the channel is determined to be idle; re-determining, by the processor, if the channel is occupied; and determining if the CW counter is 1 when the channel is re-determined to be occupied; and wherein if the CW counter is 1, then the BE is set to a first value, and wherein if the CW counter is not 1, then the BE is set to a second value that is different than the first value.

2. The method as claimed in claim 1 , further comprising setting BE as aMaxBE when the channel is re-determined to be occupied.

3. The method as claimed in claim 1 , wherein the CW counter is initialized and BE is increased by 1 when the channel is re-determined to not be occupied.

4. A method of recognizing an available channel in order to prevent channel occupation requirements from colliding with each other when one wireless channel is shared by plural terminals in a CSMA/CA mechanism using an IEEE 802.15.4 protocol slot, in which a backoff time varies by allocating different backoff exponents (BEs) for determining a random backoff time, the method comprising: initializing, by a processor, counters, CW, and NB, as 2 and 0, respectively; waiting, by the processor, for a unit backoff period corresponding to a randomly selected integer; determining, by the processor, if a channel is occupied; decreasing, by the processor, the CW counter by 1 when the channel is determined to be idle; re-determining, by the processor, if the channel is occupied; and determining, by the processor, if the CW counter is 1 when the channel is re-determined to be occupied; wherein if the CW counter is 1, then the BE is set to a first value, and if the CW counter is not 1, then the BE is set to a second value that is different than the first value.

5. The method as claimed in claim 4 , further comprising setting BE as aBESCB, a certain value greater than aMaxBE, when the CW counter is determined to be 1.

6. The method as claimed in claim 4 , wherein when CW counter is determined not to be 1, the CW counter is initialized and BE is increased by 1.